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Green Roof Rules and Regulations

Monday, October 10, 2011

Residential Green Roofs, Small Scale, Big Impact

Genora's Green Roof, Jacksonville, Florida

Genora Orth's green roof may be considered small by some. Approximately 13' by 10' the living roof captures rain from most of the front porch portion of the historic Riverside Avondale home in Jacksonville.

Anecdotally I estimate of all stormwater flowing through and then off the entire roof, about five percent is intercepted by the living roof soil media and plants.

Individually five percent of a house's roof is not much, however collectively five percent is very significant.

On Genora's roof for example, the 130 square foot living roof over the porch captures another 200 square feet of roof run off from the area above the living roof.

Quick calculations show a two inch rainfall event across 230 square feet of roof would produce about 400 gallons of stormwater.

Normally such an amount coming off asphalt shingles would carry contaminants, not only from the petroleum based asphalt shingles but also those contaminants from the urban core atmosphere.

Jacksonville has approximately 300,000 homes and residential structures, all contributing stormwater directly or indirectly to the St. Johns River and Floridan aquifer.

If 10% of the homes in Jacksonville were to install a living roof on their front or back porch there would be a total of 30,000 homes with small green roofs. If each green roof attenuated or cleaned 400 gallons of stormwater then the total amount of treated and cleaned runoff would exceed 1,200,000 gallons.

However, just think what would happen if just half of the residential structures in Jacksonville installed small green roofs like Genora's then over 6,000,000 gallons would be cleaned and attenuated before reaching our Floridan aquifer and St. Johns River.

Now consider the fact that it is estimated there are several million residential structures in Florida. If each had a small green roof like Genora's living roof then close to a billion gallons of stormwater runoff could be intercepted and cleaned before reaching our waters.

Just as the tree lady of India, Janet Yegneswaran plants one tree at a time, small green roofs could cover the urban and suburban core one roof at a time.

Genora's efforts make a strong statement of sustainability, providing us with an example and a challenge to do something ourselves to help clean our rivers, streams and waterbodies.

Green roofs don't have to be big to impact the world. Small scale green roofs carry a message of powerful intent.

16 comments:

You made a pretty accurate calculation. If the government plans to implement this as a project, I hope the community will participate in it. As you've said, if the green roof is capable of absorbing 5 percent of rainwater, then this can help prevent flooding whenever there are heavy rains. Aside from that, this can also help lower air pollution.

True, a green roof can definitely go a long way. This type of roof helps in purifying the air, as the plants absorb carbon dioxide and emit clean and pure oxygen for us to breathe. I hope green roofs can be furthered globally, so the air can be made cleaner and purer for generations to come.

I agree with you, Adam! Green roofs promote air quality. The green roofing system actually decreases the “heat island effect” – the main reason of Ozone Production. With this, a safer and fresher environment can be guaranteed for the inhabitants, their offspring, and nature itself.

I am speechless after seeing these pictures! I love them all! I teach kindergarten and I'm going to make a theme, and photographs have given me so many ideas! You are so talented! Thanks! New Roof North East

Small acts, when compounded, are a strong tool to restore and save nature. What I love about green roof is that it enhances air quality by filtering the air particles from the atmosphere through the vegetation on the roof.

Well, this just proves that you don’t need to have a spacious roof to have a green roof of your own. All you need to know is that what type of green roof is suitable for you. This is great, as in a very simple way, you get to help save the environment!